Sometimes we "like" something that is not correct just because so many people say it incorrectly that we have become used to it. The who/whom question comes to mind. Many do not use these correctly because there are so few modeling them correctly.
The "possessive in front of the gerund" is one such thing.
The gerund is the "-ing" form of the verb used as a noun.
...Reading is my favorite pastime. ("Reading" is the subject of the sentence.)
...I enjoy reading. ("Reading" is the direct object.)
...He is tired of reading about it. ("Reading" is the object of the preposition.)
The rule for the noun or pronoun form in front of the gerund is that it is in the possessive case.
...I enjoy John's reading to me.
...I enjoy his reading to me.
Enjoying John is different from enjoying his reading.
...I am tired of Mr. Martin's trying to convince me.
...I am tired of his trying to convince me.
You are not necessarily tired of Mr. Martin.
...There is a necessity of its being correct.
...It is a result of our caring about her.
Happy punctuating!
Margie